A moving image gives the impression that an object moves continuously as a series of still images are displayed at a speed of 24 fps or 60 fps. In a case where a viewer sees a moving image without moving the line of sight, there is no sense of discomfort in many cases. However, as in the attraction of a 360-degree field of view and the projection mapping for the moving object, in a case where the line of sight of the viewer follows the projected image moving at a high speed, or a moving image is projected on an object moving at a high speed, it is known that a sense of discomfort such as feeling the movement of the image intermittently may occur.
Therefore, by using a high-speed projection element such as a digital micromirror device (DMD), for example, it is conceivable to project a moving image at a speed (frame rate) of 1,000 fps. However, if the image is to be displayed in full color (24-bit color), the response speed of the DMD is also insufficient, and the amount of computation required for image rendering becomes enormous, which makes it difficult to handle with Codec or GPU of the related art. In addition, a video transmission standard such as HDMI (registered trademark) is also not suitable for transmission of such a large amount of data.
In PTL1, it is assumed that each pixel of moving image is composed of a plurality of segments divided in time and each segment is composed of a plurality of subfields, weighting is applied to luminance in each subfield, and a technique for obtaining a desired intermediate gradation depending on which subfield is to be combined for each pixel is described. However, a relatively large number of segments are set in order to achieve a high gradation, and the required computation and transmission processing are to be performed in a short time, and if a moving image is to be projected or displayed at a high frame rate, it is difficult to achieve a sufficiently high gradation in a commercially available device.
In the field of projection mapping for moving objects, which is under development in recent years, a device that performs high-speed display at 1000 fps while measuring with Ir pattern light by combining a digital micromirror device (DMD) and a high-speed camera is used. In this case, it is necessary to perform the display pattern control at a high speed, and for example, it is possible to create a gradation of video by turning ON/OFF the mirror of the DMD in a time division manner. However, in the case of performing video projection while inserting Ir pattern light therebetween, since it is necessary to update the entire screen area, even with the speed of the DMD, the number of gradations that may be configured in 1/1000 second is small. For example, when three colors of RGB are used and the gradation is displayed by 4 bits, the gradation becomes insufficient because the colors become 12-bit color. In addition, even when Ir pattern light is not inserted, in a case where a moving image of a high frame rate is to be played on a moving object, it is still necessary to update the entire screen at the frame boundary, so the number of gradations that may be configured in 1/1000 second decreases.
The present disclosure aims to play a moving image at a high speed and with a high gradation under the constraints imposed by display devices such as DMD or transmission and processing devices.